Effects of human interferon and alpha-difluoromethylornithine on T47D cells

The effect of human interferon (IFN) and alpha-difluoromethylornithine (DFMO), an enzyme-activated irreversible inhibitor of eukaryotic ornithine decarboxylase, on the rate of DNA synthesis and the increase of ornithine decarboxylase activity of T47D cells was examined. It was found that IFN or DFMO alone causes little or appreciable inhibition of the [3H]thymidine incorporation, respectively. Each of the drugs alone has a significant inhibitory effect on ornithine decarboxylase activity. Combination of the two drugs has a synergistic effect and eliminates completely the [3H]thymidine incorporation and the activity of ornithine decarboxylase. The biological implication of IFN and DFMO is discussed with regard to the regulation of ornithine decarboxylase activity and the antiproliferative effects of the two drugs.